Not Applicable.
The present invention relates generally to the field of pattern recognition. More specifically, the present invention relates to a system, method and apparatus for pattern recognition that is usable in real-time symbol recognition applications.
In many cases, cathode ray tubes (CRT""s) are no longer available to repair or replace older display systems. Therefore, a demand exists to replace these displays with newly designed display systems that utilize liquid crystal display (LCD) flat-panel technology. But the electrical interface to existing CRT-based displays is often incompatible with the requirements of LCD-based displays because of the differences between these two technologies. The primary incompatibility of these two technologies is in the way that the individual pixels of each display type are selected for illumination. LCD technology employs a mechanism for discretely selecting individual pixels, whereas CRT technology employs analog voltage signals to position one or more electron beams on the display surface.
Moreover, display processing systems for real-time applications, such as for avionics displays, generally incorporate a hardware vector generation (i.e., line drawing) capability. This hardware provides digital outputs for selecting X horizontal) and Y (vertical) display screen locations, and digital video to specify the selected intensity and/or color. A separate video on/off output may also be provided. For a calligraphic/stroke type of CRT display, the X, Y, and video signals are converted to analog to directly control the position and intensity of the CRT electron beam(s). The symbol generator hardware then directly refreshes the display by executing its commands at a rate of approximately 60 HZ. For a dynamic display format, the command-list/program should be updated at a rate that is high enough to achieve smooth motion of the symbology. This may require an update rate of 20 or 30 HZ.
For LCD technologyxe2x80x94or for a raster type of CRT-based displayxe2x80x94the display screen is refreshed from a 2-dimensional frame buffer memory, or xe2x80x9cimage memoryxe2x80x9d. An image memory can be an exact 2-D mapping of the pixels of the display screen, whereby each memory location holds a code that determines the color/intensity of its corresponding pixel. The digital X and Y outputs of the symbol generator are then used to address the 2-D image memory. Vectors are written/drawn into image memory instead of directly on the display screen. For real-time applications, a symbol generator is used to update the display format in one image memory while another image memory, which contains the previous update, is simultaneously used to refresh the display screen. Therefore, some CRT-based displays are designed to alternate between stroke and raster in a hybrid mode in order to overlay stroke symbology onto raster video.
Avionics display systems often employ separate physical units for the display function and the symbol generator function. Stroke and hybrid CRT displays may utilize an analog interface between the symbol generator and the display unit. If the CRT displays are replaced with newer LCD-based units, it may be cost prohibitive to also replace the symbol generator. The new LCD-based display unit should then be designed to function with the existing analog interface. But because LCD technology employs a discrete type of pixel addressing mechanism, this tends to diminish the quality of the displayed symbology.
Accordingly, there is a need for a system, method and apparatus to recognize the patterns generated by an existing symbol generator and provide an interface between the signal generator analog interface and a new LCD or raster based display.
The following summary of the invention is provided to facilitate an understanding of some of the innovative features unique to the present invention, and is not intended to be a full description. A full appreciation of the various aspects of the invention can be gained by taking the entire specification, claims, drawings, and abstract as a whole.
One embodiment of the present invention provides a system, method and apparatus for converting an analog x-deflection signal, an analog y-deflection signal and an analog color signal into a digital image. The analog x-deflection signal, the analog y-deflection signal and the analog color signal are converted into a digital x-value, a digital y-value and a digital color value. The present invention then detects changes in the digital x-value and the digital y-value, and determines whether the detected changes correspond to a known pattern. When the detected changes correspond to the known pattern the digital color value is rendered into the digital image using one or more vectors corresponding to the known pattern. When the detected changes do not correspond to the known pattern the digital color value is written into the digital image at the corresponding digital x-value and digital y-value.
Another embodiment of the present invention provides an apparatus comprising a deflection interface, a video interface, a pattern detector, a vector generator, a rendering circuit, a first selector and a second selector. The deflection interface converts the analog x-deflection signal and the analog y-deflection signal into a digital x-value and a digital y-value. The video interface to convert the analog color signal into a digital color value. The pattern detector is coupled to the deflection interface and the video interface to detect changes in the digital x-value and the digital y-value and determine whether the detected changes correspond to a known pattern. The vector generator coupled to the pattern detector to generate one or more vectors corresponding to the known pattern. The rendering circuit is coupled to the vector generator. The first selector is coupled to the rendering circuit and the deflection interface. The second selector is coupled to the rendering circuit and the video interface. The first selector and the second selector render the digital color value into the digital image using the one or more vectors whenever the detected changes correspond to the known pattern. The first selector and the second selector also write the digital color value into the digital image at the corresponding digital x-value and digital y-value whenever the detected changes do not correspond to the known pattern.
Yet another embodiment of the present invention provides a system comprising a raster type video display, a video memory coupled to the raster type video display and an analog to digital video interface. The analog to digital interface comprises an interface, a detection circuit coupled to the interface, a pattern detector coupled to the detection circuit, a rendering circuit is coupled to the pattern detector and a selector is coupled to the rendering circuit, the interface and the video memory. The interface converts the analog x-deflection signal, the analog y-deflection signal and the analog color signal into a digital x-value, a digital y-value and a digital color value. The detection circuit detects changes in the digital x-value and the digital y-value. The pattern detector determines whether the detected changes correspond to a known pattern. The selector renders the digital color value into the digital image stored in the video memory using one or more vectors corresponding to the known pattern whenever the detected changes correspond to the known pattern. The selector also writes the digital color value into the digital image stored in the video memory at the corresponding digital x-value and digital y-value whenever the detected changes do not correspond to the known pattern.
The novel features of the present invention will become apparent to those of skill in the art upon examination of the following detailed description of the invention or can be learned by practice of the present invention. It should be understood, however, that the detailed description of the invention and the specific examples presented, while indicating certain embodiments of the present invention, are provided for illustration purposes only because various changes and modifications within the spirit and scope of the invention will become apparent to those of skill in the art from the detailed description of the invention and claims that follow.